Conversion breech plug for muzzleloading rifles to receive shotgun primers and method of using the same

ABSTRACT

A breech plug for a muzzleloading rifle has an elongated body with external threads and having rearward and forward ends. A circular depression is formed in the rearward end of the body and is surrounded by an annular rim. The annular rim has an inner diameter slightly less than the diameter of a bore of the barrel of the rifle. The depression has a tapered bottom surface that slopes inwardly and rearwardly and terminates in a first center bore extending longitudinally along a center axis of the body. A narrow diameter bore connects the first center bore with a second bore having a diameter substantially the same as the first center bore. The second center bore terminates in an enlarged bore portion adapted to receive a propellant material. The first center bore provides an expansion chamber for a large percussion element to be ignited in the depression. The narrow diameter bore allows the products of combustion from the first center bore to enter the second center bore, but prevents blowback in a reverse direction from the combustion of powder downstream from the second bore. The depression has a diameter substantially twice the diameter of the first center bore.

BACKGROUND OF THE INVENTION

[0001] Conventional modern muzzleloading rifles typically use percussion caps to ignite the powder forwardly of the breech plug. It is not conveniently possible to increase the ignition of the powder by a larger primer, such as a shotgun primer, because the size and space limitations of the breech will not permit this to happen. As a result, the operator is limited to the use of only percussion caps.

[0002] It is therefore a principal object of this invention to provide a conversion kit for muzzleloading rifles which includes both a modified breech plug and hammer to replace the existing similar components which will easily accommodate a shotgun primer.

[0003] It is therefore a further object of the invention to provide such a conversion kit which can be easily installed and used.

[0004] These and other objects will be apparent to those skilled in the art.

SUMMARY OF THE INVENTION

[0005] A breech plug for a muzzleloading rifle has an elongated body with external threads and having rearward and forward ends. A circular depression is formed in the rearward end of the body and is surrounded by an annular rim. The annular rim has an inner diameter slightly less than the diameter of a bore of the barrel of the rifle. The depression has a tapered bottom surface that slopes inwardly and rearwardly and terminates in a first center bore extending longitudinally along a center axis of the body. A narrow diameter bore connects the first center bore with a second bore having a diameter substantially the same as the first center bore. The second center bore terminates in an enlarged bore portion adapted to receive a propellant material. The first center bore provides an expansion chamber for a large percussion element ignited in the depression. The narrow diameter bore allows the products of combustion from the first center bore to enter the second center bore, but prevents blowback in a reverse direction from the combustion of powder downstream from the second bore. The depression has a diameter substantially twice the diameter of the first center bore.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a perspective view of a conventional muzzleloading rifle to which the conversion kit of this invention is adapted;

[0007]FIG. 2 is a side elevational view at an enlarged scale of the breech plug of this invention;

[0008]FIG. 3 is an elongated sectional view of the breech plug of FIG. 1;

[0009]FIG. 4 is a sectional view of the muzzleloading rifle of FIG. 1 into which the breech plug of FIGS. 2 and 3 has been inserted; and

[0010]FIG. 5 is a plan view of a tool used to facilitate the conversion of a conventional muzzleloading rifle to utilize a shotgun primer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] With reference to FIG. 1, the muzzleloading rifle 10 has a stock 12 and a conventional hollow barrel 14. A conventional receiver 16 is located at the rearward end of the barrel. A conventional trigger assembly 18 is operatively connected to the bolt and striking pin assembly 20 which includes striking pin 22. (See modified assembly 20, FIG. 4).

[0012] With reference to FIGS. 2, 3 and 4, the breech plug 24 has an elongated body 26 and has conventional threads 28 on its outer surface which are complimentary to internal threads 30 within the rearward end of the barrel. (FIG. 4) A circular depression 32 is formed in the forward end of the breech plug and has an annular rim 34 extending therearound. The rim 34 has a diameter substantially equal to that of the elongated bore 14A of the barrel 14.

[0013] The depression 32 has a bottom 36 which communicates with a first center bore 38 which is centered on the depression 32. The first center bore 38 has a tapered wall 39 which effects the connection of bore 38 with a narrow diameter center bore 40 which in turn communicates with a second center bore 42. The diameters of bores 38 and 42 are substantially the same. The bore 42 terminates in a cylindrical chamber 44 at its rearward end, having a slightly tapered sidewall 48, and enlarged rim 50.

[0014] The numeral 46 designates a shotgun primer that is adapted to fit within chamber 44.

[0015] The protruding striker point 48 (FIG. 4) of striking pin 22 is particularly adapted to rupture and ignite the primer 46 when the rifle 10 is converted for use to accommodate the primer 46.

[0016] When it is desired to convert the rifle 10 to use the primer 46, the conventional breech plug and bolt assembly of the existing rifle are removed therefrom. The breech plug 24 with its threads 28 are identical to the threads of the removed breech plug so that the breech plug 24 can be inserted back into the barrel 14 in the same position as the removed breech plug. FIG. 4 shows the breech plug 24 in that position. Similarly, the bolt and striking pin assembly 20 has the same configuration, except for striking point 48, as the removed assembly. With the rifle open, the shotgun primer 46 is inserted into the chamber 44 of breech plug 24 through the breech opening 16A. The rifle is then loaded so as to have a suitable propellant forwardly of the breech plug 24 contained in the cylindrical center bore 32.

[0017] When the rifle is fired through the conventional connection between trigger assembly 18 and bolt and striking pin assembly 20, the striking point 48 on the striking pin 22 ruptures and ignites the shotgun primer 46. The flames of combustion are permitted to expand within the bore 42 which is in direct communication with narrow center bore 40. The products of combustion are then channeled through the narrow center bore 40 and then to move directly forwardly for contact with the powder within bore 38. The ignition of the propellant in bore 38 is directed forwardly because it cannot easily blow back through the narrow center bore 40 between the bores 38 and 42.

[0018] The tool 52 in FIG. 5 is then used to remove the used primer 46 from the receiver. The same tool 52 is used to facilitate the replacement of the used primer 46 with a new one. The tool 52 has a terminal end 54 comprised of an enlarged open slot 56 to slidably embrace the sidewall 48 of primer 46. An annular groove 58 in slot 56 slidably receives rim 50 of primer 46.

[0019] It is therefore seen that the conversion of a conventional muzzleloading rifle to a rifle with an enlarged ignition system can be easily facilitated. Once this has been done, and if the original conventional breech plug is reintroduced into the rifle, the bolt and striking pin assembly with the striking pin 22 can be left in the rifle, for it will also be effective to ignite a percussion cap. The breech plug 24 is adapted to receive a 209 primer.

[0020] It is therefore seen that this invention will achieve at least all of its stated objectives. 

What is claimed is:
 1. A breech plug for a muzzleloading rifle comprising: an elongated body with external threads and having rearward and forward ends, a circular depression in the rearward end of the body surrounded by an annular rim, the annular rim having an inner diameter slightly less than the diameter of the bore of the barrel, the depression having a tapered bottom surface that slopes inwardly and rearwardly and terminating in a first center bore extending longitudinally along a center axis of the body, a narrow diameter bore connecting the first center bore with a second center bore having a diameter substantially the same on the first center bore, the second center bore terminating in a chamber portion, the second center bore providing an expansion chamber for a percussion element ignited in the chamber portion adjacent the second center bore, and the narrow diameter bore allowing products of combustion from the second center bore to enter the first center bore, but preventing blowback in a reverse direction from the explosion of powder within the first center bore.
 2. The breech plug of claim 1 wherein enlarged bore portion has tapered side walls.
 3. The breech plug of claim 1 wherein the depression has a diameter substantially twice that of the diameter of the second center bore.
 4. A method of converting a conventional muzzleloading rifle having a breech plug threadably inserted into the rearward end of a rifle barrel, and having a rearward end fitted only to receive a rifle primer, or ignition by a striking pin, comprising removing the striking pin and the breech plug from the rifle, replacing the removed breech plug with a conversion breech plug having threads identical to those of the removed breech plug and having a rearward end capable of receiving a shotgun primer, using a striker pin capable of igniting the shotgun primer when the striker pin is actuated, providing an expansion chamber immediately forwardly of the shotgun primer, placing a narrow diameter restricter passageway forwardly of the expansion chamber, placing a second elongated chamber having a diameter substantially the same as the diameter of the expansion chamber immediately forward of the small diameter conduit, and placing a propellant material in a forward end of the second center bore, whereby the ignition of the propellant will take place by igniting the shotgun primer wherein the products of combustion will move through the narrow diameter restricter passageway and thence into the second center bore to ignite the propellant material, whereby the blowback effect of the ignited propellant material towards the expansion chamber through the restricted narrow diameter restricter passageway will be prevented. 